This invention relates generally to cooling and heating refrigeration systems and, more particularly, to a flow valve such as for use in an absorption cooling and heating refrigeration system to appropriately reverse fluid flow in the system.
Absorption cooling and heating systems are well known. In such a system operated in a cooling mode, a generator heats a refrigerant solution comprising a "strong" or concentrated solution of a more-volatile or refrigerant component in a less-volatile or solvent component. The heat drives the refrigerant from the strong solution to separate a refrigerant vapor, leaving a "weak solution" that is depleted of the refrigerant.
Where the refrigerant solution is a solution of a non-volatile solute in a volatile solvent, such as lithium bromide in water, the "weak solution" contains a higher concentration of the solute but a lower concentration of the solvent than the corresponding "strong solution." Where the refrigerant solution is a solution of a more volatile solute in a less-volatile solvent, such as ammonia in water, the "weak solution" is depleted of ammonia and is mostly water, while the "strong solution" is a more concentrated ammonia solution.
After being separated in the generator, the refrigerant vapor leaves the generator, flowing to a first phase change heat exchange device operated as a condenser. In the condenser the refrigerant vapor is placed under pressure and heat is removed to an external heat sink. As a result, the vapor condenses to form a refrigerant liquid. After leaving the condenser, the refrigerant liquid flows to a second phase change heat exchange device operated as an evaporator. The evaporator relieves the pressure on the refrigerant liquid and the refrigerant evaporates, again forming a vapor. This evaporation of the refrigerant draws heat from a heat load and creates the cooling effect of a refrigerator or air conditioner.
The refrigerant vapor from the evaporator flows to an absorber. The weak solution formed in the generator also flows to the absorber. In the absorber, the weak solution reabsorbs the refrigerant, reforming the strong solution. The strong solution then flows back to the generator and the cycle repeats.
The same system can be operated in a heating mode by reversing operation of the first and second phase change heat exchange devices such that the first phase change heat exchange device now operates as an evaporator and the second phase change heat exchange device operates as a condenser, with the associated heat inputs and outputs correspondingly also being reversed.
For a heating and cooling system to capably operate efficiently alternatively in both heating and cooling modes will generally require the utilization of flow control means whereby the fluid flow through particular system components can be appropriately reversed with no more than minimal or acceptable fluid leakage. As a result, there is a need and a demand for a flow control valve for use in such systems whereby the fluid flow through particular system components can be efficiently and appropriately reversed while avoiding undesired or excessive fluid leakage.